This invention relates to an apparatus, especially an extruding apparatus, for producing corrugated foamed plastic sheets.
Conventional methods for producing thermoplastic synthetic resin foams having depressed and raised portions such as a corrugated shape essentially involve first preparing a foamed sheet having a flat surface, and then shaping it by means of a heated mold or roll. These methods, however, have the defect that they entail an after-shaping step and require additional devices for this step, and the cellular structure of the surface of the resulting corrugated foamed plastic sheet is destroyed thereby deteriorating the properties of the foamed plastic sheet.
It is an object of this invention therefore to provide an apparatus for easily producing corrugated foamed plastic sheets having superior properties from lesser amounts of raw material without impairing the superior properties of the foams and without the need to shape or otherwise process the resulting foamed plastic sheet for corrugation.
Extensive investigations in an attempt to eliminate the defects of the conventional techniques and to achieve the object of this invention led to the development of the present invention.